diff --git a/riscv-c-api.md b/riscv-c-api.md
index 23f1115..bd0b1a1 100644
--- a/riscv-c-api.md
+++ b/riscv-c-api.md
@@ -127,12 +127,12 @@ marco could be used in intrinsic interface or user program directly.
 
 | Type Name             | Meaning                              |
 | --------------------- | ------------------------------------ |
-| int_xlen_t            | Signed integer type with XLEN bits   |
-| uint_xlen_t           | Unsigned integer type with XLEN bits |
+| int_xlen_t            | Two's-complement signed integer type with exactly XLEN bits (no padding bits)   |
+| uint_xlen_t           | Unsigned integer type with exactly XLEN bits (no padding bits) |
 
 | Macro Name            | Value                                |
 | --------------------- | ------------------------------------ |
-| INT_XLEN_MAX          | Minimum value of int_xlen_t          |
+| INT_XLEN_MAX          | Maximum value of int_xlen_t          |
 | INT_XLEN_MIN          | Minimum value of int_xlen_t          |
 | UINT_XLEN_MAX         | Maximum value of uint_xlen_t         |
 | UINT_XLEN_MIN         | Minimum value of uint_xlen_t         |